MONTREAL — Bombardier Inc. won a resounding victory Friday when the U.S. International Trade Commission eliminated nearly 300% in duties on its C Series commercial jet by unanimously voting against a petition filed by Boeing Co.

The decision was a surprise for some observers who expected the commission would side with Boeing even though they believed the company sustained no harm. Even one government official said it wouldn’t be surprised by a loss.

The decision caused Bombardier’s stock to shoot up to its highest level in three years. Shares gained nearly 15% to $3.52 after the ruling.

Bombardier also called it a victory for U.S. airlines and the American travelling public.

“With this matter behind us, we are moving full speed ahead with finalizing our partnership with Airbus,” it added.

Full speed ahead on the C Series partnership! Senior Leaders from Airbus and Bombardier meeting in Montreal today to discuss integration planning. pic.twitter.com/bwrClKtpwa

“We are disappointed that the International Trade Commission did not recognize the harm that Boeing has suffered from the billions of dollars in illegal government subsidies that the Department of Commerce found Bombardier received and used to dump aircraft in the U.S. small single-aisle airplane market,” it said in a statement.

“Those violations have harmed the U.S. aerospace industry, and we are feeling the effects of those unfair business practices in the market every day.”

Boeing said it will continue to document any harm to Boeing from illegal subsidies and dumping pricing.

“We will not stand by as Bombardier’s illegal business practices continue to harm American workers and the aerospace industry they support. Global trade only works if everyone adheres to the rules we have all agreed to. That’s a belief we will continue to defend.”

Boeing launched the trade case last April, arguing that governments in Canada and Britain subsidized the plane’s development and allowed Bombardier to sell it at unfairly low prices.